Well this is actually demonstrably false. Biden currently has the house and the senate, Trump has the house, the senate and the Supreme Court, Obama had the house and the senate… The rhetoric between these two sides is substantially different, but the governments they produce are very similar. They implement some token fraction of the policy platform they were elected on, and otherwise just plow through the same old policy agenda every time. Who’s opposing this Tory Online Safety bill in the UK? Technically Labour is, but only because they think it doesn’t go far enough…
No he doesn't, the Republicans hold the House. And while a bare majority is sufficient to pass legislation in the House, the Senate has this quasi-official filibuster nonsense which means it's hard to get a lot of things done without a supermajority. Additionally, any legislative change is typically immediately dragged into court which can slow down implementation for several years.
The American right and left are very different when it comes to policy platform, and electing one or the other actually does have a measurable difference on what ends up happening to people in the country. This is especially true when we consider minority groups.
I agree that both sides are mainly interested in consolidating power and increasing the scope of government's oversight of people's lives. But even if I use your terminology, the "left wing tyrants" and "right wing tyrants", if one or the other were given complete control of the country... well, the country would look very different after some time, depending on which side were given control.